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Table 5 DMD disability domains: item content and factor loadings where applicable

From: Measuring Duchenne muscular dystrophy impact: development of a proxy-reported measure derived from PROMIS item banks

Domain Variable name Item content Inclusion by ambulation status** CFA standardized factor loadings^
Fatigue impact
  fatig1 My child got tired easily ATN 0.81
  fatig2 Being tired made it hard for my child to keep up with schoolwork ATN 0.94
  fatig3 My child had trouble starting things because he/she was too tired ATN 0.95
  fatig4 My child was so tired it was hard for him/her to pay attention ATN 0.93
  fatig6 My child was too tired to enjoy the things he/she likes to do ATN 0.89
Strength impact
  str1 My child was strong enough to open a heavy door ATN 0.82
  str2 My child was strong enough to pour a drink from a full pitcher or carton ATN 0.97
  str3 My child could open a jar by himself/herself ATN 0.88
  str4 My child was strong enough to raise his arms over his/her head ATN 0.81
Upper extremity function
  upper1 My child could button his/her shirt or pants ATN 0.95
  upper2 My child could open the rings in school binders ATN 0.95
  upper3 My child could pull a shirt on over his/her head without help ATN 0.93
  upper4 My child could put on his/her shoes without help ATN 0.85
  upper5 My child could use a key to unlock a door ATN 0.94
Cognition function
  cog1 Your child reacts slower than most people his/her age when he/she plays games ATN 0.78
  cog2 It is hard for your child to find his/her way to a place that he/she has visited several times before ATN 0.85
  cog3 It is hard for your child to pay attention to one thing for more than 5–10 min ATN 0.86
  cog4 Your child has to read things several times to understand them ATN 0.88
  cog6 It is hard for your child to understand pictures that show how to make something ATN 0.91
  cog7 It is hard for your child to add or subtract numbers in his/her head ATN 0.84
  cog8 Your child has to use written lists more often than other people his/her age so he/she will not forget things ATN 0.90
  cog9 It is hard for your child to find the right words to say what he/she means ATN 0.87
  cog10 Your child has trouble recalling the names of things ATN 0.90
Negative affect (Bifactor model)
Anger affect1 My child felt mad ATN 0.74
Anxiety affect2 My child felt nervous ATN 0.81
Anxiety affect3 My child felt scared ATN 0.79
Anxiety affect4 My child felt worried ATN 0.87
Anxiety affect5 It was hard for my child to relax ATN 0.88
Depression affect6 My child felt lonely ATN 0.64
Depression affect7 My child felt sad ATN 0.81
Depression affect8 My child didn't care about anything ATN 0.69
Anger stress1 Small things upset my child ATN 0.71
Positive affect
  peer2 My child felt a sense of belonging around his peers ATN 0.66
  pos1 My child felt happy ATN 0.92
  pos3 My child was in a good mood ATN 0.94
  pos4 My child felt calm ATN 0.81
  mob1 My child could get in and out of a car ATN NA
  mob2 My child could do sports and exercise that other kids his/her age could do ATN NA
  mob3 My child could get up from a regular toilet ATN NA
  mob4 My child could keep up when he/she played with other kids ATN NA
  mob5 My child has been physically able to do the activities he/she enjoys most ATN NA
  mob6 My child could get up from the floor AT NA
  mob7 My child could walk more than one block AT NA
mob8 My child could ride a bike AT NA
mob9 My child could walk across the room AT NA
  mob10 My child could run a mile A NA
  mob11 My child used a wheelchair to get around ATN NA
  mob12 My child used a medical scooter to get around ATN NA
  mob13 My child could move his/her legs N NA
Sleep-device symptoms*
  sleep3 My child had muscle-cramping during the night ATN NA
  sleep4 My child's leg braces were uncomfortable during the night TN NA
  sleep5 My child was on a breathing machine at night (C-PAP or Bi-PAP) ATN NA
  sleep6 My child had difficulty changing positions in his sleep TN NA
  1. Two different response options for the mobility items: never to almost always for all but mob11 and mob12; and with no trouble to not able to do for all others
  2. Original PROMIS Parent Proxy items are reprinted with permission from The Assessment Center
  3. ^For the bifactor model, the loadings correspond to the general factor
  4. *Clinimetric index
  5. **A = Ambulatory, T = Transitional, N = Non-ambulatory